Light responsive apparatus



Dec. 8, 1936. P. H. CRAGO LIGHT RESPONSIVE APPARATUS INVENTOR Filed Oct. 27 1934 I D D 7 Paul HCmgo. Fig. 5 fl/fiw HIS ATTORNEY Patented Dec. 8, 1936 UNITED STATES.

PATENT OFFICE 2,063,298 uon'r aasronsrvs APPARATUS Paul a. Crago, Wilkinsburg, Pa, assignor to The Union Switch & Signal Company, Swissvale Pa., a corporation of Pennsylvania Application October 27, 1934, Serial No. 750,345

10 Claims.

My invention relates to light responsive apparatus, and has. for an object the provision of novel and improved means for controlling an electrical device in response to the action of 5 light. 7

I will describe three forms of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a dia- 10 grammatic view showing one form of apparatus embodying my invention. Fig. 2 is a view showing one form of vehicle detecting system also embodying my invention. Fig. 3 is a view showing another form of vehicle detecting system 15 embodying my invention.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Fig. 1, the reference character A designates a device having a magnetizo able core 2 provided with two windings W and W", so that these windings are in mutual inductive relation. The first winding W is provided with a circuit including a source of alternating current the terminals of which are designated 25 X and Y, and the primary P of a transformer T. The secondary S of transformer T is connected with the input terminals of a full wave rectifier R, and the output terminals of this rectifier are connected with a direct current relay B.

30 The winding W of the device A is provided with a shunt which includes light responsive means characterized by relatively high resistance when dark, and relatively low resistance when subjected to the action of light. As here 35 shown, this means comprises two light sensitive cells C and each having a relatively high resistance in both directions when dark, and each having a relatively low resistance in at least one direction when subjected to the action of light.

40 These cells C and C are connected in multiple in the shunt around winding W and are oppositely poled, so that when the cells are subjected to the action of light, the resistance of the shunt is materially reduced.

45 The reference character L designates a source of light, such as an electric lamp, the rays from which may be concentrated on the cells C and C by suitable optical means, such as a lens D.

' The parts of the apparatus are so proportioned 50 that when the lamp L is extinguished, so that the cells C and C are dark, with the result that the resistance of the shunt around winding W isrelatively high, the impedance of winding W is such that the current in transformer T is not 66 suillcient to effectively energize relay 3; whereas when the lamp L is lighted, so that the resistance of theshunt around winding W is relatively low, the impedance of winding W is reduced to such an extent that enough current will flow in transformer T to effectively energize 5 relay B.

It should be pointed out that while in Fig. 1, the shunt for winding W is shown as comprising two oppositely poled light sensitive cells con- .nected in multiple, satisfactory operation of the apparatus can be obtained with a single cell by properly proportioning the parts.

Referring now to Fig. 2, the reference character H designates a stretch of railway track which is equipped with vehicle detecting apparatus embodying my invention. This apparatus is the same as the apparatus shown in Fig. 1, except that the two light responsive cells C and C are located at spaced intervals along the track and are provided with individual light sources L and L respectively. Each cell and its associated source of light are located on opposite sides of the track and are so arranged that the cell normally receives light from its associated source but that the rays are intercepted by a vehicle moving along the track. In this case the parts are so proportioned that relay B will become deenergized when the rays of light to either cell are interrupted, and will subsequently remain deenergized until both cells are again illuminated.

The operation of the apparatus shown in Fig.

2 is as follows: Normally both cells C and C are lighted so that relay B is energized. When a car or train passes either cell, it will intercept the light rays normally striking such cell, whereupon relay B will release. When relay B once releases, it will subsequently remain released until both cells are again illuminated.

Referring now to Fig. 3, the apparatus here shown is similar to that shown in Fig. 2 with the exception that the polarity of the cell C has been reversed, so that both cells C and C now have the same polarity relative to winding W; and the parts are so proportioned that relay B will pick up when either cell is illuminated, but will release when and only when both cells are dark.

With the apparatus arranged in this manner when a car or train traverses stretch H, relay B will become released if and 0 1y if both beams 5 become simultaneously intercepted by the car or train, and when the relay once becomes released it will remain released only so long as both beams remain dark. It will be seen, therefore, that the result of this arrangement isto provide an M .of the car or train less the distance between the light beams.

It will be seen from the foregoing that I have provided means for controlling a direct current relay by means of light sensitive cells without supplying the power for the relay directly from the light sensitive cells.

Although I have herein shown and described only three forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a first and a second winding in mutual inductive relation, a circuit for said first winding including a source of alternating current, a relay receiving energy from said circuit, a closed circuit for said second winding including light responsive means characterized by relatively high resistance when dark and relatively low resistance when subjected to the action of light, and means for at times subject-' responsive means is subjected to the action of light the reduced resistance of said closed circuit reduces the impedance of said first winding to such value that said relay becomes effectively energized.

2. In combination, a first and a second wind ing in mutual inductive relation, a circuit for said first winding including a source of alternating current, a relay receiving energy from said circuit, a, closed circuit for said second winding including two light responsive devices connected in multiple each having relatively high resistance in both directions when dark and each having relatively low resistance in at least one direction when subjected to the action of light, said devices being oppositely poled in said closed circuit so that when they are subjected to the action of .light the resistance of said shunt is materially reduced, and means for at times subjecting said devices to the action of light, said parts being so proportioned that when said devices are dark the impedance of said first winding is such that said relay is not effectively energized whereas when the resistance of said closed circuit is reduced by the action of light on said devices the impedance of said first winding is reduced to such value that saidrelay becomes efiectively energized.

3. In combination, a first and a second winding in mutual inductive relation, a circuit for said first winding including a source of alternating current and the primary of a transformer, a relay connected with the secondary of said transformer, a closed circuit for said second winding including light responsive means characterized by relatively high resistance when dark and relatively low resistance when subjected to the action of light, and means for at times subjecting said light responsive means to the action of light, said parts being so proportioned that when said light responsive means is dark the impedance of said first winding is such that said relay is not effectively energized whereas when said light responsive means is subjected to the action of light the reduced resistance of said closed circuit reduces the impedance of said first winding to such value that said relay becomes effectively energized.

4. In combination, a first and a second winding in mutual inductive relation, a circuit for said first winding including a source of alternating current and the primary of a transformer, a relay connected with the secondary of said transformer, a closed circuit for said second winding including two devices connected in multiple each having relatively high resistance in both directions when dark and each having relatively low resistance in at least one direction when subjected to the action of light, said devices being oppositely poled in said closed circuit so that when they are subjected to the action of light the resistance of said closed circuit is materially reduced, and means for at times subjecting said devices to the action of light, said parts being so proportioned that when said devices are dark the impedance of said first winding is such that said relay is not effectively energized whereas when the resistance of said closed circuit is reduced by the action of light on said devices the impedance of said first winding is reduced to such value that said relay becomes eflectively energized.

' 5. In combination, a first and a second winding in mutual inductive relation, a circuit for said first winding including a source of alternating current and the primary of a transformer, a relay connected with the secondary of said transformer, a full wave rectifier interposed between said secondary and said relay, a closed circuit for said second winding including light responsive means characterized by relatively high resistance when dark and relatively low resistance when subjected to the action of light, and means for at times subjecting said light responsive means to the action of light, said parts being so proportioned that when said light responsive means is dark the impedance of said first winding is such that said relay is not eifectively energized whereas when said light responsive means is subjected to the action of light the reduced resistance of said closed circuit reduces the impedance of said first winding to such value that said relay becomes eifectively energized.

6. In combination, a first and a second winding in mutual inductive relation, a circuit for said first winding including a source of alternating current and the primary of a transformer, a relay connected with the secondary of said transformer, a full wave rectifier interposed between said secondary and said relay, a closed circuit for said second winding including two devices connected in multiple each having relatively high resistance in both directions when dark and each having relatively low resistance in at least one direction when subjected to the action of light, said devices being oppositely poled in said closed circuit so that when they are subjected to the action of light the resistance of said shunt is materially reduced, and means for at times subjecting said devices to the action of light, said parts being so proportioned that when said devices are dark the impedance of said first winding is such that said relay is not effectively energized whereas when the resistance of said closed circuit is reduced by the action of light on said devices the impedance of said first winding is reduced to such value that said relay becomes efiectively energized.

7. .In combination, a first and a second wind.

ing in mutual inductive relation, a circuit for said first winding including a source of alternateing current, a relay receiving energy from said circuit, two closed circuits for said second winding each including a light responsive device characterized by relatively high'resistance when dark and relatively low resistance when subjected to the action of light, and means for at times subjecting each of said devices to the action of light, said partsbeing so proportioned that when either of said devices is dark the impedance of said first winding is such that said relay 'is not eiiectively energized, whereas when both of said devices are subjected to the action of light the reduced resistance of said closed circuits reduces the impedance of said first winding to such value that said relay becomes efiectively energized.

8. In combination, a stretch of railway track, a first and a second winding in mutual inductive relation, a circuit for said first winding including a source of alternating current, a relay receiving energy from said circuit, two light responsive devices located at spaced points along said stretch of track and characterizedby relatively high resistance when dark and relatively low resistance when subjected to the action of light, a source of light associated with each said device and arranged to be intercepted by a vehicle moving along said track, and two closed circuits for said second winding each including a diflerent one of said light responsive devices, said parts being so proportioned that when either of said devices is dark the impedance of said first winding is such that said relay is not eifectively energized, whereas when both of said devices are subjected to the action of light the reduced resistance of said closed circuits reduces the impedance of said first winding to such value that said relay becomes eflectively energized.

9. In combination, a first and a second winding in mutual inductive relation, a circuit for said first winding including a source of alternating current, a relay receiving energy from said circuit, a closed circuit for said second winding including two light responsive cells connected in multiple and each having relatively high resisting relatively low resistance in at least one direction when subjected to the action 01 light, said cells being similarly poled with relation to said winding, and means for at times subjecting said devices to the action of light, the parts being so proportioned that the impedance of said first winding will be such that said relay will not be efiectively energized except when both said cells are subjected to the action of light.

10. In combination, a stretch of railway track, a first and a second winding in mutual inductive relation, a circuit for said first winding including a source of alternating current, a relay receiving energy from said circuit, two light responsive devices located at spaced points along said stretch of track and characterized by relatively high resistance when darlr and relatively low resistance when subjected to the action of light, a source of light associated with each said device and arranged to be intercepted by a vehicle moving along said track, and two closed circuits for said second winding each including a different one of said light responsive devices, the parts being so proportioned that when either of said devices is illuminated the impedance of said first winding will be such that said relay will be efiectively energized, whereas when both of said devices are dark the impedance of said first winding will then be such that said relay will not be effectively energized.

PAUL H CRAGO.

I ance in both directions when dark and each hav- 

